Study on the Opening and Modifying of MWNTs

Abstract:

Article Preview

Different opening and modifying methods of MWNTs are studied and compared in this paper.
MWNTs are dipped in a refluxed HNO3 solution. The influence of temperature, concentration and
holding time on the opening and modifying of MWNTs is studied. The compared process is that MWNTs
are treated by O3. The solvent that can highly dissolve O3 and disperse MWNTs is crucial. In order to
prompt the reaction, 1M CF3COOH is elected as reactant medium and catalysis. The opening of MWNTs
is tested by BET and confirmed by TEM. The surface structure of MWNTs treated by different processes
is analyzed by FT-IR. The optimum conditions of opening and modifying of MWNTs are discussed.

Abstract: A novel evaluation method of pozzolanic activity of metakaoline is studied. The pozzolanic activity can be evaluated by the measurement of the content of AlO4 tetrahedra. Base on this method, the influence of calcination time on pozzolanic activity of metakaoline is studied. The results indicate that the pozzolanic activity increases with the calcination time when calcination time is below 4 hours, and it decreases with the calcinations time increasing when the calcination time is 4-8 hours.

Abstract: In this paper, super fine LiMn2O4 powder was synthesized by mechanochemical method starting from Li2CO3 and Mn2O3. The structure, size and morphology of LiMn2O4 were explored with X-ray diffraction and scanning electron microscopy (SEM). The electrochemical properties of LiMn2O4 were studied in 2 mol/L (NH4)2SO4 solution. The result showed that pure spinel LiMn204 powder was prepared after 8h grinding with 3.0KW of power and the particle size was about 1µm. Cyclic vohammetry curve indicate LiMn2O4 electrode material has better capacitive performances.

Abstract: Bismuth neodymium ferrite (Bi1-xNdxFeO3: BNFO; x=0, 0.025, 0.075, 0.125, 0.175) ceramics were prepared by a co-precipitation method and sintered at 800 °C, using nitrates as precursors. The crystal structure and dielectric properties of the samples were characterized by X-ray diffraction （XRD）and dielectric permittivity measurement at different temperatures and frequencies. XRD suggests that the impurity phases are weakened by suitably doping x=0.075. Dielectric spectra indicate that relaxation peaks below the Néel temperature which may be produced by the effect of grain boundaries and dipoles with heating vanish after doping Nd at the same content. Complex impedance spectra manifest that the doped samples are closer to Debye-type, and the impedance rises which will lead to low leakage current.

Abstract: Spindle-like bis (8-hydroxyquinoline) iron (FeQ3) complex has been synthesized with a facile method in a mixed solvent system at room temperature for 12 h. The molecular formula of the products is speculated by the C, H and N element analysis and thermal gravimetric analysis, and Fourier-transformation infrared spectroscopy was also utilized to measure its structure, which further confirm the molecular formula of the products. The observation of field emission scanning electron microscopy and transmission electron microscopy shows that the morphology of tris (8-hydroxyquinoline) iron complex is spindle-like structure. The photoluminescence of the products were also investigated. The results indicate that the photoluminescence emission of FeQ3 spindles shows obvious blue shift contrasted with that of 8-hydroxyquinoline.